Patent GB-923160-A (GB)
Title: Method and apparatus for producing twisted filament yarn
IPC: D01D5/08
Filed: 1961-10-18
Abstract: Twisted continuous filament yarn having enhanced bulk is made by extruding molten thermoplastic filament-forming polymer into plastic filaments, passing them through a cooling zone to cool the polymer from a plastic to a hardened state, collecting the filaments at a speed sufficient to impart a substantial attenuation thereto while they are being cooled, applying a peripheral effort exerted individually on the filaments <PICT:0923160/IV(a)/1> <PICT:0923160/IV(a)/2> as they are being attenuated and below where the hardening occurs to cause said filaments to become positively twisted with the twist running back along the filaments to a point above where the hardening occurs.  Specified materials include nylon, especially nylon 6, nylon 66 nylon 4, nylon 610, nylon 11 and their filamentforming copolymers, e.g. 6/66, 6/610/66, polyesters derived from terephthalic acid and ethylene glycol and from terephthalic acid and bis-1, 4-(hydroxymethyl) cyclohexane, polyethylene and polypropylene.  The process is particularly applicable to filaments of non-circular crosssection, e.g. of X- or Y-shaped, triangular, square, polygonal or other multilobal shape.  Apparatus as shown comprises a spinneret 11 for extruding the polymer in a molten condition in a yarn path extending generally downward along a vertical extrusion line at a predetermined extrusion rate, means 16, 17 for collecting the filaments in package form at a predetermined increased collection rate positioned below the spinneret, a spinning chamber 14 adapted to receive the streams of polymer immediately upon extrusion thereof wherein the streams are cooled into hardened filaments, at least one rotatably-mounted twist imparting member (e.g. 26, 27) having a continuous helical rib projecting therefrom and extending longitudinally thereof, said member or members being positioned within the chamber in the yarn path at a point where the streams normally have been cooled into hardened filaments, whereby the filaments are twisted individually by a peripheral effort on the filaments exerted by said members with the twist running back toward the spinneret beyond the point where the filaments become hardened. As shown, two spaced apart rotatably mounted twist-imparting members may be provided, their long axes being substantially perpendicular with respect to the extrusion axis, means being provided for rotating said members, e.g. electric motors 32, 33 and each member comprising two rotatably mounted shafts of circular cross-section, a continuous helical rib 29 projecting from and extending longitudinally of each of said shafts.  Preferably the spinning chamber is an elongated chamber positioned above the collecting means, the twist-imparting means being positioned in the yarn path in the lower half of the spinning chamber, the height of the ribs 29 being less than half the distance across the cross-section of the filaments 12.  Wall 25 of chamber 14 is constructed of gas-permeable material through which a cooling gas is blown, and the filaments 12 contact the left side of member 26 and the right side of member 27, without being wrapped around either member.